In this paper, we have proposed two new Routing, spectrum and core allocation (RSCA) schemes for offline survivable space division multiplexing elastic optical network (SDM-EON) supporting multi-class (mc) traffic in temporal domain. Multipath based protection scheme is applied to ensure survivability against single link failure, thus allowing traffic for each connection to be split amongst those paths. Advanced reservation (AR), being a part of multi-class traffic can withstand some delay from its time of arrival. Two schemes are designed based on the service of AR connections: all the split traffic in the multiple paths for a connection at the source node are set to start (i) at the same time strictly (mc-RSCA-S) and (ii) in a relaxed way by allowing different permissible times (mc-RSCA-R). Mixed integer linear programming (MILP) models are formulated for both the schemes. RSCA problem being an NP-hard one, those MILPs are not tractable and two heuristics with polynomial time complexity are developed. Two heuristics are based on a greedy approach and a simulated annealing (SA) based approach. Simulation studies of MILPs and the respective heuristics confirm that near optimal solutions are obtained by the proposed heuristics in identical experimental setup. It is observed that with an increase in the number of cores as well as in the percentage of AR connections in the incoming request set, spectrum utilization in the network and fragmentation of cores get reduced more by SA based approach compared to greedy approach.

We study the performance of a cognitive small cell network, catering multicast services to multiple groups of secondary users, using a pre-assigned set of orthogonal channels of primary users present in the corresponding macrocell. We consider the hybrid mode of cognitive radio operation for efficient spectrum access, where cooperative spectrum sensing is performed by the collocated secondary users of each group to ensure better protection to primary users' communication. Considering delay-sensitive application for each multicast group and availability of a rate adaptive application layer and a power adaptive link layer, we aim to maximize the energy efficiency of the small cell base station using a cross-layer approach. More precisely, a joint optimization problem involving sensing time, rate and power allocation is formulated to maximize the energy efficiency of the small cell network under the probabilistic interference constraint of each primary user and heterogeneous quality of service constraints of each SU multicast group. The problem is found to be generally non-convex and an iterative algorithm is proposed to find either an optimal or a near-optimal solution. Simulation results are presented to analyze the performance of our proposed scheme in terms of energy efficiency concerning some key system parameters. The results confirm that our solution is much more energy-efficient than the conventional approach with only transmit power adaptation.

This study outlines a non‐orthogonal multiple access (NOMA) scheme for cooperative multicasting in a cognitive radio network. The network consists of a common base station (BS), which serves a primary user multicast group (PU‐MG) and a secondary user MG (SU‐MG). The SU‐MG is located in between the BS and the PU‐MG. Their proposed spectrum sharing protocol comprises of three transmission phases. The first phase is utilised by the BS for multicasting both PUs' and SUs' signals, using NOMA transmission. In the second phase, to overcome fading impairments, the BS exploits spatial diversity among SUs, by seeking their cooperation to relay PUs' message signal. The BS, as an incentive, leases a time slot in the third phase, exclusively for supporting multicast to SU‐MG over PUs' licenced spectrum. Analytical expressions for outage probabilities of both PU‐MG and SU‐MG are derived and validated using simulations. Furthermore, outage performance of PUs and ergodic capacity of SUs are compared with a prominent recent scheme.